1. Field of the Invention
The present invention generally relates to a sampling methodology. PMore particularly, the present invention is directed to a method and apparatus utilizing a luminescence spectroscopy to detect bioaerosols and alert of the presence of a potentially pathogenic bioaerosol.
2. Description of the Related Art
Aerosols of biological origin, whether formed intentionally or unintentionally, represent a potential threat of infection by pathogens. This threat is particularly daunting in the context of closed spaces, such as buildings. A variety of methods directed to identifying harmful biological materials are known. One of the known methods is based on the principles of the luminescence spectroscopy and is concerned with the production, measurement, and interpretation of electromagnetic spectra arising from either emission or absorption of radiant energy by various substances.
One aspect of the luminescence spectroscopy provides for the ability of biological materials to fluoresce due to the presence of proteins that possess certain amino acids. Fluorescence occurs when fluorophores and fluorescent particles absorb light at a given wavelength and then immediately emit light at a longer wavelength. Although not all particles fluoresce, some bio-aerosols contain intrinsic fluorophores that could potentially be used to tag the sample as a bioaerosol. Common fluorophores found in bioaerosol are, for example, Nicotinamide Adenine Dinucleotide (NADH), Tryptophan, Tyrosine, and Riboflavin. Each of these flurophores is characterized by respective peak excitation and corresponding emission wavelengths.
The primary fluorescent amino acids are tyrosine and tryptophan. The latter compound absorbs and emits at longer wavelengths and is less likely to have spectral overlaps with compounds that are not of a biological origin. However, there are still many environmental elements and hydrocarbons that will also fluoresce in the same wavelength as tryptophan, let alone the rest of the above-mentioned fluorophores.
Another aspect of the luminescence spectroscopy that may provide a tool for detecting biological materials is phosphorescence. As compared to fluorescence, phosphorescence is characterized by the time delay emission signal that allows for time-resolution to be used as a discriminator between samples that fluoresce versus those that phosphoresce. Hence, it is possible to delay the detection of the signal until after the light source has been extinguished and the fluorescent signal has disappeared. In addition to the time delay, Tryptophan phosphoresces at a longer emission wavelength.
Most of the known biological detectors incorporate fluorescence as a means for detecting the presence of a biological aerosol. Although fluorescence is a relatively simple approach, its major disadvantage, as discussed above, is the low selectivity for the bioaerosols of interest.
Current biological aerosol detection/triggering technology including the Biological Aerosol Warning Sensor (BAWS) developed by the Massachusetts Institute of Technology and the ultra Violet Aerodynamic Particle Sizer (UVAPS) developed by TSI is acceptable. However, these instruments are expensive, power hungry, large, and require complex algorithms to determine relatively little information.
A need, therefore, exists for a methodology either perfecting or complementing a fluorescence detection technique and for an inexpensive, low power, robust apparatus carrying out the inventive methodology.
Thus, one of the objects of the present invention is to provide a method for detecting pathogenic bioaerosols having a secondary detection technique to complement fluorescence.
Another object of the present invention is to provide an apparatus for carrying out the inventive method and capable of effectively collecting bioaerosols and selectively detecting the presence of the biological materials of interest contained in the bioaerosols.
Still another object of the present invention is to provide the inventive apparatus adapted to generate a warning upon detecting the biological materials of interest and to trigger secondary, more sophisticated, equipment for the confirmation of the initially detected materials and their further identification.
A further object of the present invention is to provide the inventive apparatus characterized by a simple, space- and cost-efficient structure.
Yet another object of the invention is to provide a detection system including multiple inventive apparatuses and deployed in a single location to provide added discrimination of actual threat levels.